Windows Update-- the easy to understand way.....

Manually reset the Windows Updates Components once again and then re-initiate the Windows Update process.

Resetting Windows Update Components will fix corrupt Windows Update Components and help you to install the Windows Updates quickly.

Please follow the below steps to reset the Windows Updates Components:

1. Press Windows Key + X on the keyboard and then select “Command Prompt (Admin)” from the menu.  (right click on CMD-"run as administrator")

2. Stop the BITS, Cryptographic, MSI Installer and the Windows Update Services. To do this, type the following commands at a command prompt. Press the “ENTER” key after you type each command.

                           net stop wuauserv

                           net stop cryptSvc

                           net stop bits

                           net stop msiserver

3. Now rename the SoftwareDistribution and Catroot2 folder.

                         C:\Windows\SoftwareDistribution-- Rename to SoftwareDistribution.old

                         C:\Windows\System32\catroot2-- Rename to Catroot2.old

(Make sure the processes have been stopped so that you are able to rename the folders)

4. Now, restart the BITS, Cryptographic, MSI Installer and the Windows Update Services. Type the following commands in the Command Prompt for this. Press the ENTER key after you type each command.

                        net start wuauserv

                        net start cryptSvc

                        net start bits

                        net start msiserver

5. Type Exit in the Command Prompt to close it and then restart the computer.

6.After restarting the computer, now retry to install Windows Updates.

Ref: https://support.microsoft.com/en-us/kb/971058



This process finally worked for me to be able to install Windows 10 on my Windows 7 Desktop computer.